Understanding how genes are expressed at the appropriate times in the appropriate tissues is a central problem in the study of animal development. Experimental manipulation of the pattern of gene expression in development may be possible for the alcohol dehydrogenase genes from the Hawaiian Drosophila. Under the control of cis-acting factors, each of these closely related genes display different patterns of developmentally regulated expression. The nature of these cis-acting factors will be studied by using P element-mediated transformation to carry out interspecific transfer of genes. This will provide an in vivo assay for developmentally correct gene expression. Then, in vitro recombinations will be made between genes which are regulated in dramatically different ways, and these constructions will be similarly assayed. The approach is different from in vitro mutagenesis in that it examines the sequences that control developmentally correct expression rather than those that are minimally needed for expression. Potentially, cis-acting sequences controlling the tissue-specific expression of these genes can be delimited by this procedure. Study of the cis-acting regulatory information that influences when and where a gene is expressed would aid in elucidation of the processes underlying normal development, abnormal development and aging in man. In addition, much will be learned about the transfer of genetic information between insect species. Gene transfer provides a possible method of biological control for insects that are vectors for human pathogens.